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In our family we have 3 xf,s . The one we are having a problem with is a 2008 2.7d . My son who owns it gets a RP message that only appears when the car is getting warm and not when cold . We have pinned it down to MAF correlation between A and B , and also B has low air reading . We have a icarsoft LR 2 diagnostic unit and the reading we get from the MAF,s are as follows . When cold , circuit A is at 11 g/s and B is at 9 g/s , after running for a while A is the same but B drops to around 4. We then raise the engine speed to 2000rpm , A,s readings goes up to around 32 g/s and B stays at around 8 g/s . It then goes into RP mode and as you raise up the revs to 2500 to 3000, the B reading catches up with A and both reading are fairly even at 40 + give or take and then it comes out of RP mode . If you sit and rev the engine up and down the reading are fairly even and RP mode does not appear . The drivers side turbo you can hear spools up when cold but then when warm is quieter, it then can be heard again when revved and reading are fairly equal . When he first got it was in perminent RP mode and I changed the egrs that are now functioning ok . I have been through the port valves which hold vaccum , checked all the pre turbo hoses , changed the MAFS , turbo actuators work fine , vacuum hoses are sound , smoke tested the inlets. As said the problem occures when the car startes to warm up , when cold both G/S readings from both MAFS are equal , give or take . There is one thing that I have seen , the crank case breather does go to that side turbo inlet pipe but I cannot find anything to say that this opens when pressure has built up or is tempreture controlled as if it was open and not closing it would make a difference to the volume of air on that side . I did find a thread about this problem but as usual it did not give the cure . Has anyone had this problem . Many Thanks
 
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